John cox



`the quality of the leather.

PATENT cerros.

UNITED sTATns 'JOHN COX, OF GORGIE `MILLS,` SCOTLAND.

TANNING.

.speciacation of Letters Patent Nb. 3,614, dated June 5, 1844.

To all LU/wm t may concern:

Be it known that I, JoHNCox, a subject of the Queen of Great Britain,and now residing at Gorgie Mills, Edinburgh, within that part of Hersaid Majestys `United `Kingdom of Great Britain and Ireland calledScotland, tanner and `glue maker, have invented or discovered certainnew: and Improved `Processes of Tanning Leather; and I,.the said JOHNCox, do hereby declare the nature of my said invention and the manner inwhich the same is to be performed are fully described and ascertained inandby the following statement thereof, that is to say- `The nature of myimproved processes of tanning consists in superior methods to any `yetpracticed of the application of the principle ofinfiltration orpercolation produced by hydro-static `pressure of tanning liquor throughthe lfibers and pores of hides and skins when :formed into a bag,thereby saving timeVlabor and capitaland` improving` Various have beenthe methods hitherto attempted or proposed to facilitate the tanning ofhides and skins by causing percolation of tanning liquor through theirpores but these always have been attended with great inconvenience andexpense in the working, or the leather produced has been unequallytanned and inferior in colorV and quality. rIhe processes I am nowaboutto describe remedy more or less allthese disadvantages.

After the hides and skins have been pre pared in the usual way (as iswell understood) or `by the assistance of my prepara- `tory process (tobe afterward describec for the tanning liquor each isito be made into a`bag by carefully sewingthe. corresponding good pack thread so `as tocause as little waste as possible of any part of the said hides andskins or more hides and skins than one or only a part ,or parts thereofmay be so formed into a. bag but in all cases leaving an aperture at anyconvenient place by which the tanning liquor can be introducedthereinand taking care to sew or close up any holes that may otherwiseexist on the hides or skins` that they may contain the liquor the moresecurely. In this state of bags they are in aicondition to undergo or besubmitted to any of my improved processes of tanning but previous tocommencing `handlethem in liquor in the usual way for `a daytor two.

My first improved processof tanning is upon the principle ofinfiltration of liquor 4.through the pores and fibers of `hides andskins, butit is better calculated ithanother processes to save space andquantity of liquor requisite at a time and prevent any over distentionof the fibers. The.hide or skin being formed into a bag as beforementioned I confine or support it within `a narrow compartment or stalla (see Figure l of the annexed drawing) say four inches (more or less)wide and sufficiently long and deepas fully to contain the saidbag whenfree from lfolds or wrinkles. It is necessary that the partitionsforminglthe sides ofthe compartment or stall @should be of an uniformcontinuous smooth surface or `nearly so and not Vracked or rough i(which has been found not to succeed) so that the hide or skin shall notbe injured or `marked or unequally tanned `from unequalreaction orsupport tothe hydrostatic pressure but that the reaction orsupport ofthepartitionsshall be exactly equal to the hydrostatic pressure at anygivenpartofthe-hide or skin in contact with them. I prefer thatthepartitionsbe made of wood as smooth as possible but which may belined with clothor other porous. substance if wished which however is not necessary. Theliquor is to be supplied `to the hide or skinibag bybeing lifted up byla lpump Z), or otherwise to;a cistern c placedabove the level of thesaid partitions when by fixing a tube d intotheaperture left in thehide,-and `which tube Z shall also be connected with `the said cistern cliquor will` How into the hide bag when liquor is contained in the saidcistern- When the liquor is introduced into the bag lwhich `is placedinto the compartment care must be taken to keep it free `from wrinklesorfolds by drawing it upward and lengthwise as it fills so that thesurface of t-he hide or skin may be pressed `uniformly and smoothlyagainst the sides of the compartment. In tanning in a compartment Iprefer `that the belly of the hide or skin should be placed uppermostand that the partitions of the compartment be placed vertically andparallel to each other and ofsuch strength that they `will not yield orgive A.way `by the `hydrostatic pressure they will have to support.I/Vhen a series of compartments are to `be used in arow the pressurefrom one hide or bag will counterbalance that from the lone next it andthus render it unnecessary to use any strong wood for the partitions.The partitions should rest upon a good floor to which they should befirmly fixed and their tops or upper edges should be bound together bybars of wood. More than one bag may be put into a compartment if care betaken to supply them nearly equally with liquor and to prevent them frombeing wrinkled as percolation goes on although one hide be in contactwith or press against another.

My second improved process of tanning by infiltration is still moreperfect than the one above described as it causes equal percolation orequal effective pressure through or upon every part of the hide or skinand admits of said pressure being regulated to the greatest nicety andexactness from less than an ounce to several pounds per square inch soas to produce the most proper and equal degree of tension of the fibersof the hide or skin. It is also the most convenient process-can beeasily applied in existing tan yards and improves the color and qualityof the leather and causes less loss of tanning principle bydecomposition from exposure of hide and liquor to the air. This processthen is to cause percolation or infiltration of tanning liquor throughthe fibers and pores of hides and skins when sewn into bags by means ofhydro-static pressure, when the hides or skins are at the same time im#mersed in liquor. The position in which I prefer to have the hide orskin (when formed into a bag) when tanning according to this process isperpendicular in the direction of its length but it also may be confinedin a compartment as already described with the addition that the hide orskin be immersed or suspended in liquor. The pit or cistern e Fig. 2into which the hide or skin is to be immersed should be sufficientlydeep to admit of its being totally submerged in liquor without or merelytouching the bottom.

The manner in which I prefer to tan according to this process is to s-ewup the hide or skin as before mentioned but leaving the aperture for theintroduction of liquor' at the head into which I introduce and fix arigid tube g connected with a cistern L about two feet above the levelof the pit. I do not however confine myself to any given height for thefeeding cistern 7i, or liquor therein to be, which may be variedadvantageously according to the strength of the hides or skins underprocess, the strength of the liquor or stage of tanning. The connectingtube g, through which the liquor is tobe introduced into the bag shouldbe some inches in diameter (four inches being suitable) so as to admitof a plunger or rod being introduced into it occasionally to stir up thebark or sediment that may lodge at the bottom parts. The hide or skinbag be ing tied tightly at the neck end to the feeding tube g, whichtube g should be long enough to dip a little down among the liquor inthe pit e in which the bag is to be immersed, tanning liquor Vis to besupplied to the feeding cistern when the bag will swell until it cancontain no more liquor when percolation will commence and be continuedwith a vigor Vproportionally to the height of the liquor in the feedingcistern h above t-he liquor in the pit of immersion. As the bag fillswith liquor, the pit e (having been previously full) will overflow(unless the liquor is supplied from the pit of immersion e) andtherefore a run way z' must be made for the liquor to flow to areservoir 7c from which it may be pumped or lifted again to the feedingcistern and as the percolation goes on the liquor will flow to thereservoir L again to be raised and circulated as before. The hides orskins tanned according to this process may also be confined incompartments or jammed against each other for the sake of saving roomand the quant-ity of liquor necessary at a time as described as beingpracticable in the atmosphere, but I prefer that each bag should haveample room for swelling out as far as its dimensions will permit as thetanning goes on rat-her more rapidly and equally in all the parts whilethe tension generated by the hydrostatic pressure is more equalrendering the leather more equal in texture and quality. In this processof tanning there is a double hydrostatic pressure exerted a greaterwhich is exerted inside of the ag and a lesser which is exerted outsideof the bag and it is the surplus pressure (which is equal at all partsof the bag) of the one above the other that causes the percolation ofliquor' from within outward. In the processes describedI prefer that thegrain side of the hide or'skin be outward though I do notconfine myselfthereto and I also prefer that some bark or other solid tanningingredicnt be introduced into the bags Y so as to help to keep up thestrength of liquor' and to stop up any holes or apertures that may be inthe hide or skin.

Although pits are not deep enough to admit of the total immersionof thehides or skins it is of no great consequence whether the necks be abovethe liquor and thereby have rather less hydraulic pressure upon themprovided there be as much pressure as to cause them to tan nearly asquickly as the thickest part of the hide or skin. The gentle hydrostaticpressure exerted inside of the hide or skin bag when tanning accordingto this process improves the quality as it consolidates the texture ofthe leather and equalizes its rigidity and elasticity and thereby willsave the currier and shoemaker considerable trouble in setting it out orbeating it out to its natural limits of extension. For belt hides formachinery Athe tension kept up during the tan ning will be of greatbenelit as from every part being brought to an equal degree ofelasticity or rigidity unequal stretching, twisting or screwing will beprevented after the belts are cut from the hides. By increasing thehydrostatic pressure as the tanning progresses the hide or skin willstretch more nearly to its ultimate limits of tension and beingthoroughly tanned in that position its capability of future tension willbe greatly decreased. Uien the tanning is completed the sewing is to beopened or cut out to allow the liquor to escape or it may be run out bymeans of a siphon by gently elevating' the hide or skin as the liquor isrun otl2 after which it may be laid away for a short time in a pit inthe ordinary way to improve color or dried and finished as usual, carebeing taken to free it of the pack thread that may be adhering andparing oi'7 unseemly parts.

Having thus stated the nature of my improved methods of tanning and themanner of carrying the same into etlect I would have it understoodthat'I do not claim the principle of tanning hides or skins by causingpercolation of liquor by hydrostatic pressure through their pores andiibers nor the sewing of 'hides and skins into bags nor simply fillingthem with liquor when unconnected with a feeding cistern and withoutcausing additional hydrostatic pressure; but. I do claim the methods oftanning by hydrostatic pressure as described- I claiml. Tanning hidesand skins by hydrostatic pressure when formed into bags when they areconined or supported or suspended into continuous smooth sided narrowcompartments or stalls as described.

2. I claim tanning by hydrostatic pressure when a hide or skin is formedinto a bag and immersed totally or partially into liquor and eitherconlined in a continuous smooth sided compartment or allowed to eX- pandor swell to its natural dimensions witln out confinement or jammedagainst other hides and skins as described.

VJOHN ooX.

itnessesz p SAM CASPMAEL', WV. H. RITCHIE.

